1. Field of the Invention
The present invention relates to an internal indicator of a viewfinder of a camera for visually indicating photographic information in the viewfinder.
2. Description of the Related Art
An SLR (single lens reflex) camera having a multipoint distance measuring system or a multipoint focus detecting system that is provided with a plurality of focus frames (AF frames) seen in the field of view of a viewfinder for indicating focus detection zones or points is known in the art. Furthermore, this type of SLR camera in which one or more focus frame currently selected from among the plurality of focus frames lights up to inform the user of the camera which focus frames have been currently selected is also known in the art.
In such a type of camera in which the currently-selected focus frame or frames light up, there is a known type in which each focus frame is made of an array of minute prisms which are formed integrally onto a focusing screen as a light deflector. This camera is provided therein with at least one light emitter which is positioned outside the viewfinder optical path to illuminate the currently-selected focus frame or frames, so that the currently-selected focus frame or frames can be visually recognized by the user of the camera.
In this known type of camera using such a light emitter positioned outside the viewfinder optical path to illuminate the currently-selected focus frame or frames, each focus frame is illuminated by a corresponding light emitter which emits a monochromatic light (e.g., red light in the case where the light emitter is a red LED). Therefore, each focus frame can only indicate three different states at most (i.e., lighting state, non-lighting state and a flashing on-and-off state), so that each focus frame can only visually inform the camera""s user of a very limited amount of photographic information regarding the corresponding focus detection point by changing the state of indication of each focus frame.
The primary object of the present invention is to provide an internal indicator of a viewfinder of a camera for visually indicating photographic information in the viewfinder, wherein each indicating mark can be indicated in many different states to make it possible to provide the user with an increased amount of photographic information at each mark by changing the state of indication thereof.
To achieve the object mentioned above, according to an aspect of the present invention, there is provided an internal indicator of a viewfinder of a camera that includes a focusing screen on which an object image is formed through a photographic optical system of the camera; at least one optical deflector that is positioned on or in the close vicinity of the focusing screen and is provided with at least one deflecting surface; and, at least two light emitters for illuminating the optical deflector from the outside of the viewfinder optical system, which emit at least two light beams of different colors to be incident on the optical deflector.
With this arrangement, since a plurality of light emitters of different beam colors are provided for illuminating the optical deflector of the indicator, it is possible to provide the user with an increased amount of photographic information by having each mark light up in multicolor.
Preferably, the focusing screen is positioned at a position that is optically equivalent to a focal plane of the photographic optical system, an image formed on the focusing screen being viewed through the viewfinder optical system.
Preferably, the at least one optical deflector is formed integral with the focusing screen.
It is possible that the optical deflector constitutes a plurality of optical deflectors; wherein each optical deflector of the plurality of optical deflectors receives the at least two different colored light beams from respective the at least two light emitters. In such a case, the camera can be constructed as an AF SLR camera having a multipoint focus detecting system, and each of the plurality of optical deflectors can be formed as a focus frame.
In an embodiment, the optical deflector includes an array of deflection prisms, each of the plurality of deflection prisms is formed in a polygonal pyramid shape to have at least three deflecting surfaces, the direction of deflection thereof being different from each other. The corresponding light beams of different colors emitted from the light emitters are incident on the optical deflector at different directions, and are deflected via at least three deflecting surfaces of each of the array of deflection prisms so that deflected light beams of different colors can be viewed through the viewfinder optical system.
In this embodiment, it is preferable that the light emitters, provided for illuminating the optical deflector, include a red light emitter, a green light emitter and a blue light emitter, wherein red, green and blue light beams respectively emitted from the red light emitter, the green light emitter and the blue light emitter are incident on the optical deflector at different directions.
Each of the array of deflection prisms can be formed in a pyramid shape having a square base and four deflecting surfaces.
If the camera includes a mirror box in which a quick-return mirror of the camera is provided, the light emitters can be arranged under the mirror box at different angles relative to the focusing screen.
In another embodiment, the optical deflector includes an array of deflection prisms, each of the array of deflection prisms being formed as an elongated prism having a deflecting surface, the deflecting surfaces of the array of deflection prisms extending parallel to one another. The corresponding at least two light beams of different colors emitted from the at least two light emitters are incident on each of the optical deflector at a common direction, and are deflected via the deflecting surface of each of the array of deflection prisms so that deflected light beams of different colors can be viewed through the viewfinder optical system.
For instance, each of the at least two light emitters, provided for illuminating the optical deflector, includes a pair of two LEDs of different colors.
If the camera includes a mirror box in which a quick-return mirror of the camera is positioned, at least two light emitters can be arranged under the mirror box at the same angle relative to the focusing screen.
According to another aspect of the present invention, there is provided an internal indicator of a viewfinder of a camera, including: a viewfinder optical system including a focusing screen on which an object image is formed through a photographic optical system of the camera; a plurality of indicating marks, positioned on or in the close vicinity of the focusing screen, each indicating a specific point in a field of view of the viewfinder optical system, wherein each of the plurality of indicating marks constitutes an optical deflector; and a plurality of light sources for illuminating the plurality of indicating marks from the outside of an optical path of the viewfinder optical system. Each of the optical deflectors deflects light beams emitted from at least a corresponding one of the plurality of light sources so that the deflected light beams travel along the optical path of the viewfinder optical system to be viewed through the viewfinder optical system. Each of the optical deflectors includes an array of prisms each formed in a polygonal pyramid shape and having at least three deflecting surfaces, the direction of deflection thereof being different from each other. Each of the plurality of light sources includes a plurality of light emitters for emitting a corresponding plurality of light beams towards the plurality of indicating marks, respectively. The plurality of light beams emitted from the plurality of light emitters of one of the plurality of light sources are incident on the plurality of indicating marks in a first direction while the plurality of light beams emitted from the plurality of light emitters of another one of the plurality of light sources are incident on the plurality of indicating marks in a second direction that is different from the first direction. The plurality of light beams emitted from the plurality of light emitters of one of the plurality of light sources have a first color while the plurality of light beams emitted from the plurality of light emitters of another one of the plurality of light sources have a second color that is different from the first color.
According to yet another aspect of the present invention, there is provided an internal indicator of a viewfinder of a camera including: a viewfinder optical system including a focusing screen on which an object image is formed through a photographic optical system of the camera; a plurality of indicating marks, positioned on or in the close vicinity of the focusing screen, each indicating a specific point in a field of view of the viewfinder optical system, wherein each of the plurality of indicating marks constitutes an optical deflector; and a plurality of light sources for respectively illuminating the plurality of indicating marks from the outside of an optical path of the viewfinder optical system. Each of the optical deflectors deflects light beams emitted from a corresponding one of the plurality of light sources so that the deflected light beams travel along the optical path of the viewfinder optical system to be viewed through the viewfinder optical system; and each of the optical deflectors includes an array of prisms, and each of the plurality of light sources includes a plurality of light emitters for emitting light beams of at least two different colors towards a corresponding one of the plurality of indicating marks.
The present disclosure relates to subject matter contained in Japanese Patent Applications No. 10-228988 and No. 10-228989 (both filed on Aug. 13, 1998) which are expressly incorporated herein by reference in their entireties.